The present invention relates to an indexing device that holds a number of cards bearing telephone numbers or other indexes in a container having an openable cover and, more particularly, to an indexing device in which the opening speed of the openable cover is controlled.
An indexing device for holding cards bearing telephone numbers or other indexes consists of an open-topped container and a cover with an open bottom. A shaft passes through wall portions of both the container and the cover so that the cover is pivotally mounted to the container to make the cover openable. When a locking member holding the cover closed is released, the resilient force of a resilient member is used to open the cover. A large number of cards are stacked between the container and the cover. A selection device is provided for separating the cards at a desired point so that when the cover is opened the required card is exposed at the top of the stack.
In such a prior art indexing device constructed as described above, the velocity at which the cover opens depends on the resilient force of the resilient member. Therefore, the resilient member quickly opens the cover. The resultant reaction may raise the indexing device itself, if it is light in weight. Then, the device will collide with the base on which the device was placed, production a large unpleasant sound.
In an attempt to solve the foregoing problems, some indexing devices have been so designed that their containers are heavy to minimize the motion of the device when the cover opens quickly. However, limitations imposed on the usage of the indexing device make it impossible to increase the weight greatly.
The prior art indexing device encounters another problem. More specifically, the cover is equipped with card-elevating elements to elevate some cards when the cover is opened. Then, the elevated cards are held within the opened cover so that the user can have access to a desired card. However, when the cover is opened quickly as mentioned above, the cards underlying the desired card may be elevated by the card-elevating elements together with the cards above the desired one.